The present invention relates to a steering apparatus for remote control of a rudder means by using substantially two pull control cables.
In this specification, a pull control cable (hereinafter referred to as "cable") essentially consists of a conduit, e.g. a tube of a spiral tube made of at least one metal wire covered by synthetic resin on the outer surface thereof, and an inner cable, e.g. stranded metal wires, which are slidably inserted into the conduit.
Generally, a small-sized heat is equiped with a screw-type inboard or outboard engine which functions also as a rudder due to turn of the engine, or with a jet-type engine which functions also as a rudder due to turn of the jet nozzle. In the boat which has the inboard or outboard engine, the rotation of the steering wheel is transmitted through a push-pull cable which has an inner cable capable of enduring against the push-pull load. However, the push-pull cable generates some play in the longitudinal direction due to the clearance between the inner surface of the conduit and the outer surface of the push-pull inner cable inserted slidably into the conduit. Therefore, there is a defect that the direction of travel of the boat is not stable, due to the shock of the waves, or the like given to the rudder means in navigation.
The boat which has the later engine also has a defect that the direction of travel of the boat is not stable, because the jet nozzle swings to left and right in proportion of the degree of play, caused by the shock of the waves, or the like. Furthermore, the conventional rudder means which is independent of the propulsion device also has defect that the direction of travel of the boat is not stable due to play of the push-pull inner cable.
In order to avoid the above defects, an apparatus for operating the rudder means by winding of substantially two pull cables is proposed. However, in such an apparatus, the strong shock of the waves is transmitted directly to the inner cable, and reaches in the steering wheel. Therefore, the feeling of the steering is not comfortable, and the elongation of the inner cable which causes backlash so that the boat moves in a zigzag direction is generated in the relatively short term. As a result, the tension of the inner cable must be adjusted frequently.
The steering apparatus disclosed in U.S. Pat. No. 3,747,428 has two pulleys provided to the operating side and the working side, respectively, on which the inner cable is wound. In such an apparatus, the inner cable is wound on and off in response to the operation, and therefore the position of winding the inner cable on the pulley is shifted according to the amount of winding of the inner cable. As a result, the inner cable portion between the fixed position of the conduit and the pulley, inner is bent sharply resulting is breakdown. Therefore, the distance of the fixed position of the conduit from the pulley is necessarily large, and it is not avoidable that the apparatus becomes large.
All of the steering apparatuses mentioned above are somewhat dangerous and troublesome in use, because the shock force of waves added to the rudder means sometimes rotates the steering wheel rapidly.